Questions like this always make me scratch my head and wonder. Have you done rotations in both fields? They are in no way the same thing. They each require a very different set of skills. They are not the same thing that simply operates in different settings.
Good FP's are very well trained in their field. they are qualified at managing chronic medical problems, handling check ups, arranging for appropriate screenign exams, giving vaccinations, doing routine GYN exams (if they want). They handle non-emergent problems such as sore throats, viral uri's etc.
They are not trained nor qualified to handle emergent airways, acute MI's, bacterial meningitis, etc etc.
While there is some overlap (they have to recognize the signs) and there is an element of primary care in the ED (due to lack of patient education and other social issues such as no insurance etc) I am not qualified to tweak hypertensive meds, do a pap smear, arrange for mammograms or give vaccinations. Nor do I want to be.
So if you want to be both a GOOD FP adn a GOOD EMP, you need to do BOTH residencies. These fields are not the same. If you truly find that long term patient relationships are important to you, then EM is not the field for you.
it was not vital for me and thus EM is a great field. I enjoyed the long term aspect of FP but it wasn't vital. And I found the tweaking etc to be rather dull.